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Therefore

The adverbtherefore should be used with caution, as it is often at the center of run-on sentences. Therefore is not conventionally considered a conjunction, so it cannot fuse two independent clauses into a single sentence the way conjunctions like and, but, and because can.For example, the following sentences are run-ons because they use therefore as a conjunction introducing an independent clause:

The players were my heroes, therefore, my dad was my hero because he was the coach. [transcribed in Houston Chronicle]

The European Central Bank and the EU itself will not jeopardize their existence, therefore they will do everything they can to maintain the euro and, therefore, Greek solvency. [Wall Street Journal]

However, most have less difficulty in choosing their network of preference, therefore it certainly becomes a little simpler to narrow down the choices. [Headline News]

There are a few ways to fix sentences like these. One, make the clause beginning with therefore a separate sentence:

The players were my heroes. Therefore, my dad was my hero because he was the coach.